Room Temperature DBN Initiated Phospha‐Brook Rearrangement of α‐Hydroxyphosphonates to Phosphates

Abstract A series of substituted aryl phosphate esters have been synthesized from their α‐hydroxyphosphonates substrates, using DBN (1,5 diazabicyclo(4.3.0)non‐5‐ene) at room temperature, via a phospha‐Brook rearrangement. The aryl‐substrate dependence of the rearrangement was explored, and excellent yields of the phosphate esters were achieved irrespective of whether the aryl moiety was activated or unactivated. A plausible mechanism for the rearrangement has been proposed. Based on the low temperature 31 P‐NMR, the mechanism of the phospha‐Brook rearrangement is proposed to take place via an oxaphosphirane intermediate.